I've always thought that this argument really shows a lack of education more than anything. People do not understand the simple principle that you cannot have a highly radioactive substance and it be long living at the same time (this is because radiation is the process of matter being expelled from the atoms. Higher radiation levels, more matter/energy being expelled). But it also shows that people don't understand that things that things can also be dangerous and have no half life. Like lead and heavy metals don't decay and there are no safe levels of heavy metals.